/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.tom_roush.pdfbox.pdmodel.interactive.digitalsignature;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;

public class COSFilterInputStream extends FilterInputStream
{
    private final int[] byteRange;
    private long position = 0;

    public COSFilterInputStream(InputStream in, int[] byteRange)
    {
        super(in);
        this.byteRange = byteRange;
    }

    public COSFilterInputStream(byte[] in, int[] byteRange)
    {
        super(new ByteArrayInputStream(in));
        this.byteRange = byteRange;
    }

    @Override
    public int read() throws IOException
    {
        nextAvailable();
        int i = super.read();
        if (i>-1)
        {
            ++position;
        }
        return i;
    }

    @Override
    public int read(byte[] b) throws IOException
    {
        return read(b,0,b.length);
    }

    @Override
    public int read(byte[] b, int off, int len) throws IOException
    {
        if (len == 0)
        {
            return 0;
        }

        int c = read();
        if (c == -1)
        {
            return -1;
        }
        b[off] = (byte)c;

        int i = 1;
        try
        {
            for (; i < len ; i++)
            {
                c = read();
                if (c == -1)
                {
                    break;
                }
                b[off + i] = (byte)c;
            }
        }
        catch (IOException ee)
        {
        }
        return i;
    }

    private boolean inRange() throws IOException
    {
        long pos = position;
        for (int i = 0; i<byteRange.length/2;++i)
        {
            if(byteRange[i*2] <= pos &&  byteRange[i*2]+byteRange[i*2+1]>pos)
            {
                return true;
            }
        }
        return false;
    }

    private void nextAvailable() throws IOException
    {
        while (!inRange())
        {
            ++position;
            if(super.read()<0)
            {
                break;
            }
        }
    }

    public byte[] toByteArray() throws IOException
    {
        ByteArrayOutputStream byteOS = new ByteArrayOutputStream();
        byte[] buffer = new byte[1024];
        int c;
        while ((c = this.read(buffer)) != -1)
        {
            byteOS.write(buffer, 0, c);
        }
        return byteOS.toByteArray();
    }
}
